DE19842484A1 - Contents gauge for storage vessel, e.g. containing exhaust emission treatment solution used in heavy goods vehicle - Google Patents

Abstract

A storage container (1) having a top (1A), and bottom (1B) is filled with a liquid (F), such as aqueous urea, to a normal fill level (H). Two pipes (10,12), for respectively feeding and discharging liquid, extend downward, through electrically insulated ports (1D) in the top to just above the tank bottom. The pipes are also used sensor electrode probes (20;22,24), which are connected in a circuit with an AC power source (26) and a measuring device (28). Alternatively the two electrodes may be located on the inside and outside of a single dip pipe, or one electrode may take the form of an independent wand. Electrical conductance between the electrodes is dependent on the liquid wetted area of the electrodes and specific conductivity of the liquid, and instead of conductivity, electric capacitance probes may be used.

Description

The invention relates to the use of an in a Container interior of a lei imported lei tion, with the line liquid in the storage container ter can be fed and / or removed therefrom.

The invention also relates to storage containers for a liquid speed, especially for a urea solution. It affects in a first embodiment of a storage container for a Liquid with a through an opening in a container wall inserted electrically conductive line for feeding and / or for the removal of liquid. The invention relates in a second embodiment, a storage container for a liquid with a through an opening in a container line introduced for supply and / or removal of liquid.

In selective catalytic reduction (SCR process) nitrogen oxides from an exhaust gas of an internal combustion engine, in a motor vehicle in particular, is taking one Urea storage container required in the vehicle. Before The storage container becomes a new urea solution when refueling fed. While the engine is running, the stock Container of urea solution removed for nitrogen oxide degradation. Instead of the urea solution, any ammonia can be used containing or releasing reducing agent used become.

For smooth operation of the selective catalytic Reduction it is necessary the urea solution in the stock to monitor containers. For example, the level in the Storage container to be measurable: The supply of urea solution for the SCR process should be switched off when the  Level in the storage container below a certain minimum level drops. For various applications of the SCR process it should also be possible to change the fill was to conclude a consumption of urea solution, to improve control of the SCR process or Diagnosis of an associated urea solution dosing system enable.

It also aims to control selective catalytic reduc tion can switch off if the concentration of urea in the urea solution outside of a certain tolerance reichs falls if the urea solution is frozen, if There are heavy impurities in the urea solution and / or if an unsuitable liquid is in the pre was filled.

For such monitoring measurements, one or more various sensor elements introduced into the storage container the. This would make one familiar to the person skilled in the art Considered manufactured storage containers complex, prone to repair and heavy, the latter named part in particular in the field of automotive engineering pay attention.

The invention is therefore based on the object, a Ver drive to indicate with the liquid from the reservoir can be removed and / or fed to the storage container, and where the liquid in the reservoir is easy and can be monitored in a material-saving manner. It should also a storage container can be specified, which is to be carried out tion of such a method is particularly suitable.

The task related to a procedure is carried out according to the Erfin dung solved in that in the container interior of the Storage line introduced at least as part of a Sensor element or for fastening at least one part  a sensor element is used, with the sensor element ment a property of the liquid is measurable.

If the cable is used to attach the sensor element det, then there is no separate or at least only one ge small separate supporting body for the sensor element ment required. If the line is used as a sensor element det, this not only brings the advantage of a saving Material for a supporting body with it, but in addition also the advantage of saving material for the Sensor element. With the method, d. H. with the use According to the invention can therefore be liquid from a Remove or feed the container and close it without large additional material costs a property of the liquid measure up.

The line is, for example, a pipeline.

The line is preferably used as a first electrode of the Sensor element used.

According to a preferred embodiment, an electrical conductive wall of the line used as the first electrode. For example, a simple metal pipe can be used in this case the function of a line as well as the function of an elec take over trode.

But it can also be a wall of the line for fastening the Sensor element can be used. With such a configuration tion, the wall of the line also serves as a support structure for the sensor element, e.g. B. for the first electrode.

The property of the liquid is, for example, an elec tric conductivity or an electrical capacity measurable.

The electrical conductivity can be, for example, from the specific electrical conductivity of the liquid and  the size of a surface of the Detach sensor element. With the same specific electrical conductivity can then result from a change in the wetted sensor element surface on a change in the fill stands in the storage container are closed. At as the same Conversely known level in the container can be reversed a change in electrical conductivity to a change tion of the specific electrical conductivity of the liquid speed can be closed, for example by the tempe temperature, the state of matter or an ion concentration in depends on the liquid.

An electrical capacity depends, for example, on a right latent dielectric constant of the liquid and its size from a liquid-wetted sensor element surface. This is also a change in the level in the container or for example, contamination or change in physical state the liquid is detectable.

The object of the invention to provide a storage container is solved in relation to the first embodiment by that the line is integrated into an electrical circuit is.

In the "circuit" depending on the application and measured its property of the liquid u. U. even extremely ring currents flow that z. B. in a capacity measurement can tend towards zero (quasi electrostatic measurement).

For example, the line has sufficient electrical Conductivity and is particularly a metallic tube management.

The line or the part of the line that is supplied Liquid is wettable, for example with a Current or voltage source connectable. With such a Storage container in which the line has a dual function  act, namely both the function of transporting liquid speed as well as the function of an electrical conductor takes is in a particularly simple and inexpensive way the liquid in the reservoir regarding electrical Properties can be monitored.

But it can also have two lines, an inlet line and an extraction line, of which the extraction line device as the first electrode and the feed line as the second Electrode are connected.

A second electrode can e.g. B. also from an electric conductive wall of the container or from a corresponding Coating should be formed on the wall.

When measuring a capacitance of an electrically conductive Liquid it is appropriate that the line or part the line, which can be wetted with the supplied liquid, is covered with an insulating layer.

The task related to a reservoir is related to the second embodiment according to the invention solved that on the line or on the part of the line, the is wettable with supplied liquid, at least a part a sensor element is attached.

The line is, for example, one - especially metallic - pipeline.

The line is not only used in this embodiment Transport of the liquid in or out of the storage container ter, but also as a supporting structure or as a supporting probe body. Such a storage container is particularly simple, inexpensive to manufacture and with low material consumption.

On the line or on the named part of the line especially a first electrode of the sensor element  brings. The electrode can be used, for example, for the measurement electrical conductivity or for measuring a electrical capacity.

According to a preferred embodiment of the storage container the opening arranged in a ceiling wall, the pipe with one end inserted close to the bottom of the container, and he most electrode extends substantially along the ge entire introduced line.

With a first electrode attached in this way, measure the fill level of the container in a particularly simple manner. The second electrode required as a counter electrode of the sensor element can, for example, through the container wall or part of the container wall.

With a first electrode designed in this way is before electrical conductivity measurable.

A second electrode of the sensor element is preferably on attached to the line or to a part of the line.

According to a particularly preferred further development of the store is the first electrode on an outside of the Lei tion attached, and on an inside of the line second electrode attached.

An electrical capacitance can thus preferably be measured. If the liquid is electrically conductive, are the two Electrodes electrically isolated from each other. This can expediently one of the electrodes with an insulation be coated.

The second electrode can also be through the liquid itself be formed insofar as this is electrically conductive. The Liquid, which then z. B. at any point in the loading container via a contact element or a contact pin in the  electrical circuit is integrated, then acts as an elec trode, the surface of which depending on the level variable value. The first electrode, either is formed by the line or on the line is then used for the purpose of a capacity measurement electrically isolated from the liquid.

According to another preferred embodiment of the supply store the opening is arranged in a ceiling wall One end of the line is inserted close to the bottom of the tank, and at the end a third electrode with little expansion attached along the line.

The third electrode is in such a configuration Wet the storage container with liquid only if the Level is above a minimum level.

As a counter electrode to the third electrode, for example the first electrode must be connected. A first measuring device in a first circuit, the first and the second Includes electrode, is then for example for measurement a fill level of the storage container available. A second Measuring device in a second circuit, which the third elec trode and also includes the first electrode, can then be provided for the detection of a measurement signal which consists of finally from a specific property of the liquid speed, for example a concentration of dissolved ions in of the liquid or the temperature of the liquid. This measurement signal is the one measured by the first measuring device Level of the container with respect to a specific change Change of the liquid can be corrected and therefore an extremely ex Current measure for the fill level or a change in fill level winable.

The devices are preferred for carrying out the method suitable.

Six exemplary embodiments of a storage container according to the invention are explained in more detail with reference to FIGS. 1 to 10. Show it:

Fig. 1 shows a first embodiment of a Vorratsbehäl ters according to the invention (first embodiment),

Fig. 2 shows a second embodiment of a Vorratsbehäl ters, according to the invention (second embodiment)

Fig. 3 shows a third embodiment of a Vorratsbehäl ters, according to the invention (second embodiment) in a side view

Fig. 4 shows a section along the line IV-IV of Fig. 3,

Fig. 5 shows a fourth embodiment of a Vorratsbehäl ters of the invention (second embodiment) in a side view;

Fig. 6 shows a section along the line VI-VI of Fig. 5,

Fig. 7 shows a fifth embodiment of a Vorratsbehäl ters of the invention (second embodiment) in a side view;

Fig. 8 is a section along the line VIII-VIII of Fig. 7,

Fig. 9 shows a sixth embodiment of a Vorratsbe hälters according to the invention (first embodiment) in a side view;

Fig. 10 is a section along the line XX of Fig. 9.

Fig. 1 shows a storage container 1 according to the invention in a first embodiment. The container 1 comprises a top wall 1, and a container bottom 1 B. The interior of the container 1 C is filled with a fluid F, a urea solution to a level H. The liquid surface is designated 3 . Through two openings 1 D, a tubular inlet line 10 (inlet direction 11 ) and a tubular discharge line 12 (outlet direction 13 ) are introduced into the storage tank 1 up to close to the tank bottom 1 B.

A sensor element 20 comprises a first electrode 22 and a second electrode 24 , the first electrode 22 being formed by the extraction line 12 and the second electrode 24 being formed by the feed line 10 . The electrodes 22 , 24 are integrated in an electrical circuit 25 with a current or voltage source 26 and a measuring device 28 . If - as in the example - the storage container 1 consists of an electrically conductive material, the lines 10 , 12 , which are also electrically conductive, are electrically insulated from one another and from the storage container 1 by insulator pieces 32 . The current or voltage source 26 generates an alternating current or an alternating voltage.

To the electrodes 22, 24, an electrical Leitfä can ability L between the electrodes 22, measure 24th The electrical conductivity L is dependent on the level H in the container 1 and on the specific electrical conductivity σ of the liquid F.

In Fig. 2, a second embodiment of a storage container 1 is shown according to the invention, in which a sensor element 20 is attached to the end of the sampling tube or the sampling line 12 , which is connected via a measuring line 34 with a display unit 36 to. In this case, the sensor element 20 can be, for example, a temperature sensor, a conductivity sensor, a capacitance sensor, a Hall sensor, an ultrasound sensor or a pressure sensor.

In the third exemplary embodiment of a storage container 1 according to the invention shown in FIG. 3, the first electrode 22 and the second electrode 24 of the sensor element 20 are attached following the curvature of a wall 38 of the extraction line 12 . As can be seen from the cross-sectional drawing of FIG. 4, the electrodes 22 , 24 are each formed only along part of the circumference of the wall 38 , so that there is a distance between them and in a simple manner an electrical conductivity L between the electrodes 22 , 24 is measurable. An electrical contacting of the electrical 22 , 24 is omitted in Fig. 3 and the following figures for reasons of clarity. Where the Behäl terboden 1 B faceable end of the withdrawal line 12 is attached to a third electrode 40, which would look like in cross-section approximately as the second electrode 24, but along the extraction line 12 having only a smaller extent.

In the fourth exemplary embodiment of a storage container according to the invention shown in FIG. 5 and in FIG. 6, the first electrode 22 is embodied on an outer side 44 of the wall 38 as in the example shown in FIG. 3, the second electrode 24 is against it attached to an inner side 42 of the wall 38 of the sampling line 12 . With electrodes 22 , 24 designed in this way, an electrical conductivity L as a measure of the fill level H can also be determined.

In this exemplary embodiment, too, the third electrode 40 is present at the end of the extraction line 12 .

As in the aforementioned embodiment of FIG. 3, this third electrode 40 can perform a reference conductivity measurement. With the aid of such a reference measurement, a change in the conductivity signal originating from the first electrode 22 and the second electrode 24 can be unequivocally and precisely inferred from a change in the container fill level H. A change in the specific electrical conductivity σ of the liquid F would also be reflected in a change in the output signal from the third electrode 40 - with the first electrode 22 as the counterelectrode - so that this output signal can possibly be used to correct the conductivity signal .

The thickness of the electrodes 22 , 24 , 40 is shown in Fig. 3 to 8 greatly exaggerated for illustrative reasons. In practice, it is a thin coating compared to the wall thickness.

In the fifth and sixth exemplary embodiment shown in FIGS . 7 to 10, the fill level H in the container 1 is determined by measuring an electrical capacitance C. The electrical capacitance C is dependent both on the fill level H in the container 1 and on the relative permittivity ε _{r of} the liquid F, the influence of the last-mentioned quantity being able to be compensated for, if necessary, by a reference measurement (see above).

In the fifth embodiment shown in FIG. 7 and in FIG. 8 along a cross-sectional view along the line VIII-VIII of FIG. 7, a first electrode 22 designed as a coating is applied to the removal line 12 . This first electrode 22 is coated in the area immersed in the liquid F with an insulating layer 50 , which electrically insulates the first electrode 22 from the liquid F.

In this storage container 1 , the urea solution containing and thus electrically conductive liquid F is used as a second electrode 24 , which is inserted into the circuit 25 via a contact pin 52 inserted through the container wall into the container interior 1 C. Depending on the fill level H, this second electrode 24 has a variable contact or cross-sectional area influencing the measured capacitance C with respect to the first electrode 22 . This arrangement is particularly advantageous in that the level H measured via the capacitance C depends only to a very small extent on the relative dielectric constant ε _r .

In the sixth exemplary embodiment shown in FIG. 9, a removal line 12 (outlet direction 13 ) is used as the first electrode 22 in an electrical circuit 25 with a current or voltage source 26 and a measuring device 28 . The part immersed in the liquid F of the withdrawal line 12 is of an electrically insulating insulating layer 50 , for. B. surrounded by a layer of lacquer. The withdrawal line 12 is coated both on its inside and on its outside.

FIG. 10 shows the extraction line 12 in a cross-sectional illustration along the line XX of FIG. 9.

Also in the sixth embodiment, the liquid speed F serves as a second electrode 24 , which is connected via a contact pin 52 in the circuit 25 .

Claims (15)

1. Use of a in a container interior ( 1 C) of a storage container ( 1 ) introduced line ( 10 , 12 ), with the line ( 10 , 12 ) liquid (F) in the storage container ter ( 1 ) can be supplied and / or from this can be removed, at least as part of a sensor element ( 20 ) or for fastening at least part of a sensor element ( 20 ), with the sensor element ( 20 ) a property (C, L) of the liquid (F) being measurable. 2. Use according to claim 1, characterized in that the Lei device ( 10 , 12 ) as a first electrode ( 22 ) of the Sensorelemen ts ( 20 ) is used ( Fig. 1, 9, 10). 3. Use according to claim 2, characterized in that an elec trically conductive wall ( 38 ) of the line ( 10 , 12 ) is used as the first electrode ( 22 ). 4. Use according to claim 1 or 2, characterized in that a wall ( 38 ) of the line ( 10 , 12 ) for fastening the sensor element ( 20 ) is used ( Fig. 2 to 8). 5. Use according to one of claims 1 to 4, characterized in that as Eigen shaft has an electrical conductivity (L) or an electri cal capacity (C) is measurable. 6. reservoir (1) sigkeit for a liquid (F), in particular for a urea solution, with an inserted through an opening in egg ner container wall (1 A) electrically conductive line (10, 12) for supply and / or removal of flues (F), characterized in that the Lei device ( 10 , 12 ) in an electrical circuit ( 25 ) is the ( Fig. 1, 9, 10). 7. Storage container ( 1 ) according to claim 6, characterized in that the Lei device ( 10 , 12 ) or the part of the line ( 10 , 12 ) which can be wetted with liquid to be fed (F) with a current or voltage source ( 26 ) is connectable. 8. Storage container ( 1 ) according to claim 6 or 7, characterized in that the Lei device ( 10 , 12 ) or the part of the line ( 10 , 12 ) which can be wetted with liquid to be fed (F), with an insulating layer ( 50 ) is coated. 9. reservoir (1) for a liquid (F), in particular for a urea solution, with a through opening (1 D) in a container wall (1 A) inserted line (10, 12) for supplying and / or for the removal of liquid (F), characterized in that at least part of a sensor element ( 20 ) is attached to the line ( 10 , 12 ) or to the part of the line ( 10 , 12 ) which can be wetted with supplied liquid (F) ( Fig. 2 to 8). 10. Storage container ( 1 ) according to claim 9, characterized in that on the Lei device ( 10 , 12 ) or on the part of the line ( 10 , 12 ) a ste electrode ( 22 ) of the sensor element ( 20 ) is attached. 11. Storage container ( 1 ) according to claim 10, characterized in that the opening ( 1 D) is arranged in a ceiling wall ( 1 A), and that the line ( 10 , 12 ) with one end up to the container bottom ( 1 B ) is inserted, and that the first electrode ( 22 ) extends substantially along the entire inserted line ( 10 , 12 ). 12. Storage container ( 1 ) according to one of claims 9 to 11, characterized in that a second electrode ( 24 ) of the sensor element ( 20 ) is attached to the line ( 10 , 12 ) or to the part of the line ( 10 , 12 ) . 13. Storage container ( 1 ) according to claim 12 and claim 10 or 11, characterized in that the first electrode ( 22 ) on an outer side ( 44 ) of the line ( 10 , 12 ) is attached, and in that on an inner side ( 42 ) of the Lei device ( 10 , 12 ) the second electrode ( 24 ) is attached. 14. Storage container ( 1 ) according to one of claims 9 to 13, characterized in that the opening ( 1 D) is arranged in a ceiling wall ( 1 A), and that the line ( 10 , 12 ) with one end close to the container bo the ( 1 B) is inserted, and that at the end a third electrode ( 40 ) with small expansion along the Lei device ( 10 , 12 ) is attached. 15. Storage container ( 1 ) according to one of claims 9 to 14, characterized in that the first electrode ( 22 ) and / or optionally the second electrode ( 24 ) is coated with an insulating layer ( 50 ).